The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement...The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement of simultaneous high efficiency and low reflectivity across microwave,terahertz,and infrared spectra remains a formidable challenge.Herein,a carbonized MXene/polyimide(C-MXene/PI)aerogel material integrating a spatially coupled hierarchically anisotropic structure with stepwise conductivity gradients was constructed.Electromagnetic waves propagate through the top-down vertical disordered horizontal architecture and progressive conductivity gradient of C-MXene/PI aerogel,undergoing stepwise absorption-dissipation-re-dissipation processes.The C-MXene/PI aerogel exhibits an average electromagnetic interference(EMI)shielding effectiveness of91.0 dB in X-band and a reflection coefficient of 0.40.In the terahertz frequency band,the average EMI shielding performance reaches66.2 dB with a reflection coefficient of 0.33.Furthermore,the heterolayered porous architecture of C-MXene/PI aerogels exhibits low thermal conductivity and reduced infrared emissivity,enabling exceptional infrared stealth capability across the 2-16μm wavelength spectrum.This study provides an feasible strategy for constructing low-reflectivity multi-spectrum compatible shielding materials.展开更多
Undesired ice accumulation on infrastructure and transportation systems leads to catastrophic events and significant economic losses.Although various anti-icing surfaces with photothermal effects can initially prevent...Undesired ice accumulation on infrastructure and transportation systems leads to catastrophic events and significant economic losses.Although various anti-icing surfaces with photothermal effects can initially prevent icing,any thawy droplets remaining on the horizontal surface can quickly re-freezing once the light diminishes.To address these challenges,we have developed a self-draining slippery surface(SDSS)that enables the thawy droplets to self-remove on the horizontal surface,thereby facilitating real-time anti-icing with the aid of sunlight(100 m W cm^(-2)).This is achieved by sandwiching a thin pyroelectric layer between slippery surface and photothermal film.Due to the synergy between the photothermal and pyroelectric layers,the SDSS not only maintains a high surface temperature of 19.8±2.2℃at the low temperature(-20.0±1.0℃),but also generates amount of charge through thermoelectric coupling.Thus,as cold droplets dropped on the SDSS,electrostatic force pushes the droplets off the charged surface because of the charge transfer mechanism.Even if the surface freezes overnight,the ice can melt and drain off the SDSS within 10 min of exposure to sunlight at-20.0±1.0℃,leaving a clean surface.This work provides a new perspective on the anti-icing system in the real-world environments.展开更多
The modulation of electromagnetic parameters is crucial for tuning the dielectric and magnetic properties of materials.In this work,the concentration of oxygen vacancies(VO)and the degree of lattice distortion in spin...The modulation of electromagnetic parameters is crucial for tuning the dielectric and magnetic properties of materials.In this work,the concentration of oxygen vacancies(VO)and the degree of lattice distortion in spinel oxides were successfully regulated by implementing a heteroatom doping strategy,which enhanced the structural stability as well as the optimization of the permittivity.However,the description of the polarization mechanisms in spinel structures is currently unclear.Therefore,carbon cloth(CC)surface was constructed with modified spinel structure to form nanosheet arrays(C@NMC).Localized electronic reconfiguration and altered spinel configurations were achieved by modulating manganese(Mn)substitution at specific metal sites.The lattice distortion activated dipole polarization,which increased the permittivity of the CC material to twice its original value.As a result,Mn–doped C@NMC samples(C@NMC–0.2)demonstrate a reflection loss(RL)of -63.40 dB(2.06 mm)and an effective absorption bandwidth(EAB)of 4.80 GHz.This work achieves precise regulation of dielectric properties through atomic–level defect engineering,while establishing a synergistic model between structural stability and polarization paths at the experimental level.This research provides a new perspective for an in–depth understanding of the electromagnetic loss mechanism of spinel oxides.展开更多
The development of multifunctional electromagnetic wave-absorbing materials capable of operating in complex environments has become critically important in the field of electromagnetic protection.However,achieving mat...The development of multifunctional electromagnetic wave-absorbing materials capable of operating in complex environments has become critically important in the field of electromagnetic protection.However,achieving materials that combine high absorption efficiency with exceptional thermal stability remains a significant challenge.Owing to their lightweight hollow structure,low thermal conductivity,and high thermal stability,hollow SiC/C fibers present a promising solution to the problem of hightemperature electromagnetic wave absorption.In this study,hollow SiC/C nanofibers were successfully synthesized via a combined hydrothermal and carbothermal reduction approach.The resulting hollow SiC/C nanofibers exhibit ultralight characteristics,hightemperature stability,good elasticity and fatigue resistance,and exceptional electromagnetic wave absorption performance,including an effective absorption bandwidth of 7.0 GHz at a thickness of 2.4 mm and an optimal reflection loss of−63.5 dB at a thickness of 1.4 mm.Moreover,the material demonstrates remarkable high-temperature dielectric stability,with its complex permittivity remaining virtually unchanged at 600℃.The formulated strategy provides a feasible approach for designing SiC matrix composites with stable dielectric properties and efficient electromagnetic wave absorption.展开更多
In order to alleviate the growing problem of electromagnetic radiation pollution,it is both urgent and challenging to develop electromagnetic wave absorbing materials with strong absorption and wide effective absorpti...In order to alleviate the growing problem of electromagnetic radiation pollution,it is both urgent and challenging to develop electromagnetic wave absorbing materials with strong absorption and wide effective absorption bandwidth(EAB).The structural design of heterojunction surfaces plays an important role in the development of advanced microwave absorbing materials.Building on this concept,three-dimensional nanocomposites Alk-Ti_(3)C_(2)T_(x)/nitro metal phthalocyanine(TNMP)with phthalocyanine derivative NMP-MXene are designed.TNMP composites are prepared by self-assembly of surface hydroxylated treated MXene with floral spherical nitrophthalocyanine.This method effectively constructs rich heterojunction surfaces and induces dipole polarization effect by designing a large number of oxygen vacancies through coordination,which effectively enhances the material attenuation capability while balancing impedance matching characteristics.By modulating the metal centers in the NMP,the coordination mode of the heterojunction surfaces is regulated,and the polarization relaxation loss is improved to achieve excellent electromagnetic wave absorption performance(reflection loss(RL)of-62.12 dB at a thickness of 1.25 mm).And based on the bionic structure design,a unit cycle structure of double-layered butterfly wing skeleton(DLBWS)is constructed to obtain an ultra-wideband electromagnetic wave absorber with an EAB of 12.5 GHz.This research demonstrates a regulatory scheme to elucidate the dipole polarization mechanism and proposes a new method for designing functional materials in ultra-broadband electromagnetic wave absorption.展开更多
The design and fabrication of efficient microwave absorbing materials with tunable wave attenuation capacity to address the increasing demand for electromagnetic pollution mitigators remains a challenging task.In this...The design and fabrication of efficient microwave absorbing materials with tunable wave attenuation capacity to address the increasing demand for electromagnetic pollution mitigators remains a challenging task.In this study,Ag_(2)Te and a series of Ag/Ag_(2)Te composites have been successfully synthesized by using a facile one-step solvothermal method through varying the molar ratio of the reactants and reaction time.To investigate the microwave absorption performance of these composites,the samples are mixed with polyvinylidene difluoride matrix under different filler ratios.The experimental results indicate that the AT3(where the molar ratio of Ag:Te is 4:1)sample possesses optimal wave dissipation ability with a minimum reflection loss value of−55.98 dB at 15.01 GHz and a maximum effective absorption bandwidth of 4.90 GHz(13.10-18.00 GHz)at a thickness of 1.7 mm when the filler content is 10 wt.%.Moreover,the widest EAB of 6.20 GHz(10.60-16.80 GHz)is recorded in the Ag_(2)Te sample.Meanwhile,it is observed the solvothermal reaction time can effectually influence effective wave absorption frequency.As the reaction time increases,the position of the minimum reflection loss(RLmin)shifts to lower frequencies.The analysis of the wave absorption mechanism demonstrates that the novel crooked one-dimensional linear structure and abundant heterogeneity within the Ag/Ag_(2)Te composite plays an important role in achieving outstanding wave absorption performance.The specific wave absorption mechanism includes conductive loss,multiple scattering,multiple resonant coupling,interface polarization and electric dipole polarization.This work can provide an effective strategy for the design of high-performance MAMs through constituent and morphology modulation.展开更多
Traditional cloth diapers are fully reliant on the water retention capacity of the absorbent cores to deter leaks,often overlooking the role of the top sheet,which can lead to reverse osmosis of absorbed urine.Janus m...Traditional cloth diapers are fully reliant on the water retention capacity of the absorbent cores to deter leaks,often overlooking the role of the top sheet,which can lead to reverse osmosis of absorbed urine.Janus membranes,known for their liquid diode effect,present an ideal material for the top sheet of cloth diapers.However,the widespread application of Janus membranes in cloth diapers faces challenges such as failure to meet anti-backflow requirements,limited biocompatibility,and insufficient antimicrobial properties.Here,a multifunctional Janus fabric for the top sheet of cloth diapers is developed through the synergistic combination of gradient wettability and nanoparticle functionality.The modulable gradient wettability provides unidirectional liquid transport with a high rectification ratio,which is essential for preventing liquid backflow.Consequently,prototype cloth diapers incorporating Janus fabrics as the top sheet outperform commercial products in wetback resistance.Functionalized silver nanoparticles not only provide the necessary micro-nano hierarchical structure for gradient wettability but also endow Janus fabrics with excellent chemical antibacterial properties.The integration of dryness derived from the excellent unidirectional transport performance and antibacterial properties effectively prevents bacterial growth on cloth diapers.Additionally,the Janus fabrics exhibit excellent washability and biocompatibility,further enhancing their potential applications in reusable cloth diapers.展开更多
基金supported by the Fundamental Research Funds for the Central Universities under No.2024KQ130the National Natural Science Foundation of China(No.52373259)。
文摘The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement of simultaneous high efficiency and low reflectivity across microwave,terahertz,and infrared spectra remains a formidable challenge.Herein,a carbonized MXene/polyimide(C-MXene/PI)aerogel material integrating a spatially coupled hierarchically anisotropic structure with stepwise conductivity gradients was constructed.Electromagnetic waves propagate through the top-down vertical disordered horizontal architecture and progressive conductivity gradient of C-MXene/PI aerogel,undergoing stepwise absorption-dissipation-re-dissipation processes.The C-MXene/PI aerogel exhibits an average electromagnetic interference(EMI)shielding effectiveness of91.0 dB in X-band and a reflection coefficient of 0.40.In the terahertz frequency band,the average EMI shielding performance reaches66.2 dB with a reflection coefficient of 0.33.Furthermore,the heterolayered porous architecture of C-MXene/PI aerogels exhibits low thermal conductivity and reduced infrared emissivity,enabling exceptional infrared stealth capability across the 2-16μm wavelength spectrum.This study provides an feasible strategy for constructing low-reflectivity multi-spectrum compatible shielding materials.
基金supported by the National Natural Science Foundation of China(52273101,51922018,and 21875011)the Fundamental Research Funds for the Central Universities(KG21015201 and KG21020801)China Postdoctoral Science Foundation(2025M77422)。
文摘Undesired ice accumulation on infrastructure and transportation systems leads to catastrophic events and significant economic losses.Although various anti-icing surfaces with photothermal effects can initially prevent icing,any thawy droplets remaining on the horizontal surface can quickly re-freezing once the light diminishes.To address these challenges,we have developed a self-draining slippery surface(SDSS)that enables the thawy droplets to self-remove on the horizontal surface,thereby facilitating real-time anti-icing with the aid of sunlight(100 m W cm^(-2)).This is achieved by sandwiching a thin pyroelectric layer between slippery surface and photothermal film.Due to the synergy between the photothermal and pyroelectric layers,the SDSS not only maintains a high surface temperature of 19.8±2.2℃at the low temperature(-20.0±1.0℃),but also generates amount of charge through thermoelectric coupling.Thus,as cold droplets dropped on the SDSS,electrostatic force pushes the droplets off the charged surface because of the charge transfer mechanism.Even if the surface freezes overnight,the ice can melt and drain off the SDSS within 10 min of exposure to sunlight at-20.0±1.0℃,leaving a clean surface.This work provides a new perspective on the anti-icing system in the real-world environments.
基金National Natural Science Foundation of China,Grant/Award Numbers:22505056,22575012,52373259Fundamental Research Funds for the Central Universities,Grant/Award Number:2024KQ130。
文摘The modulation of electromagnetic parameters is crucial for tuning the dielectric and magnetic properties of materials.In this work,the concentration of oxygen vacancies(VO)and the degree of lattice distortion in spinel oxides were successfully regulated by implementing a heteroatom doping strategy,which enhanced the structural stability as well as the optimization of the permittivity.However,the description of the polarization mechanisms in spinel structures is currently unclear.Therefore,carbon cloth(CC)surface was constructed with modified spinel structure to form nanosheet arrays(C@NMC).Localized electronic reconfiguration and altered spinel configurations were achieved by modulating manganese(Mn)substitution at specific metal sites.The lattice distortion activated dipole polarization,which increased the permittivity of the CC material to twice its original value.As a result,Mn–doped C@NMC samples(C@NMC–0.2)demonstrate a reflection loss(RL)of -63.40 dB(2.06 mm)and an effective absorption bandwidth(EAB)of 4.80 GHz.This work achieves precise regulation of dielectric properties through atomic–level defect engineering,while establishing a synergistic model between structural stability and polarization paths at the experimental level.This research provides a new perspective for an in–depth understanding of the electromagnetic loss mechanism of spinel oxides.
基金supported by the National Natural Science Foundation of China(Nos.22575012,22505056,and 52373259)the Research Funding of Hangzhou International Innovation Institute of Beihang University(No.2024KQ130).
文摘The development of multifunctional electromagnetic wave-absorbing materials capable of operating in complex environments has become critically important in the field of electromagnetic protection.However,achieving materials that combine high absorption efficiency with exceptional thermal stability remains a significant challenge.Owing to their lightweight hollow structure,low thermal conductivity,and high thermal stability,hollow SiC/C fibers present a promising solution to the problem of hightemperature electromagnetic wave absorption.In this study,hollow SiC/C nanofibers were successfully synthesized via a combined hydrothermal and carbothermal reduction approach.The resulting hollow SiC/C nanofibers exhibit ultralight characteristics,hightemperature stability,good elasticity and fatigue resistance,and exceptional electromagnetic wave absorption performance,including an effective absorption bandwidth of 7.0 GHz at a thickness of 2.4 mm and an optimal reflection loss of−63.5 dB at a thickness of 1.4 mm.Moreover,the material demonstrates remarkable high-temperature dielectric stability,with its complex permittivity remaining virtually unchanged at 600℃.The formulated strategy provides a feasible approach for designing SiC matrix composites with stable dielectric properties and efficient electromagnetic wave absorption.
基金supported by the Research Funding of Hangzhou International Innovation Institute of Beihang University(No.2024KQ130)the National Natural Science Foundation of China(No.52373259).
文摘In order to alleviate the growing problem of electromagnetic radiation pollution,it is both urgent and challenging to develop electromagnetic wave absorbing materials with strong absorption and wide effective absorption bandwidth(EAB).The structural design of heterojunction surfaces plays an important role in the development of advanced microwave absorbing materials.Building on this concept,three-dimensional nanocomposites Alk-Ti_(3)C_(2)T_(x)/nitro metal phthalocyanine(TNMP)with phthalocyanine derivative NMP-MXene are designed.TNMP composites are prepared by self-assembly of surface hydroxylated treated MXene with floral spherical nitrophthalocyanine.This method effectively constructs rich heterojunction surfaces and induces dipole polarization effect by designing a large number of oxygen vacancies through coordination,which effectively enhances the material attenuation capability while balancing impedance matching characteristics.By modulating the metal centers in the NMP,the coordination mode of the heterojunction surfaces is regulated,and the polarization relaxation loss is improved to achieve excellent electromagnetic wave absorption performance(reflection loss(RL)of-62.12 dB at a thickness of 1.25 mm).And based on the bionic structure design,a unit cycle structure of double-layered butterfly wing skeleton(DLBWS)is constructed to obtain an ultra-wideband electromagnetic wave absorber with an EAB of 12.5 GHz.This research demonstrates a regulatory scheme to elucidate the dipole polarization mechanism and proposes a new method for designing functional materials in ultra-broadband electromagnetic wave absorption.
基金supported by the Fundamental Research Funds for the Central Universities(No.2024KQ130)the National Natural Science Foundation of China(No.52373259).
文摘The design and fabrication of efficient microwave absorbing materials with tunable wave attenuation capacity to address the increasing demand for electromagnetic pollution mitigators remains a challenging task.In this study,Ag_(2)Te and a series of Ag/Ag_(2)Te composites have been successfully synthesized by using a facile one-step solvothermal method through varying the molar ratio of the reactants and reaction time.To investigate the microwave absorption performance of these composites,the samples are mixed with polyvinylidene difluoride matrix under different filler ratios.The experimental results indicate that the AT3(where the molar ratio of Ag:Te is 4:1)sample possesses optimal wave dissipation ability with a minimum reflection loss value of−55.98 dB at 15.01 GHz and a maximum effective absorption bandwidth of 4.90 GHz(13.10-18.00 GHz)at a thickness of 1.7 mm when the filler content is 10 wt.%.Moreover,the widest EAB of 6.20 GHz(10.60-16.80 GHz)is recorded in the Ag_(2)Te sample.Meanwhile,it is observed the solvothermal reaction time can effectually influence effective wave absorption frequency.As the reaction time increases,the position of the minimum reflection loss(RLmin)shifts to lower frequencies.The analysis of the wave absorption mechanism demonstrates that the novel crooked one-dimensional linear structure and abundant heterogeneity within the Ag/Ag_(2)Te composite plays an important role in achieving outstanding wave absorption performance.The specific wave absorption mechanism includes conductive loss,multiple scattering,multiple resonant coupling,interface polarization and electric dipole polarization.This work can provide an effective strategy for the design of high-performance MAMs through constituent and morphology modulation.
基金supported by the National Natural Science Foundation of China(52303143,22175011,52472293)China Postdoctoral Science Foundation(2021TQ0023,2022TQ0022,2022M720012)+5 种基金National Key R&D Program of China(2019YFB1309702)Beijing Young Talent Support ProgramTianmushan Laboratory Research Project(TK2023C018)Beijing Nova Program(20220484213)Key Laboratory of Icing and Anti/De-icing of China Aerodynamics Research and Development Center(IADL20230401)Fundamental Research Funds for the Central Universities。
文摘Traditional cloth diapers are fully reliant on the water retention capacity of the absorbent cores to deter leaks,often overlooking the role of the top sheet,which can lead to reverse osmosis of absorbed urine.Janus membranes,known for their liquid diode effect,present an ideal material for the top sheet of cloth diapers.However,the widespread application of Janus membranes in cloth diapers faces challenges such as failure to meet anti-backflow requirements,limited biocompatibility,and insufficient antimicrobial properties.Here,a multifunctional Janus fabric for the top sheet of cloth diapers is developed through the synergistic combination of gradient wettability and nanoparticle functionality.The modulable gradient wettability provides unidirectional liquid transport with a high rectification ratio,which is essential for preventing liquid backflow.Consequently,prototype cloth diapers incorporating Janus fabrics as the top sheet outperform commercial products in wetback resistance.Functionalized silver nanoparticles not only provide the necessary micro-nano hierarchical structure for gradient wettability but also endow Janus fabrics with excellent chemical antibacterial properties.The integration of dryness derived from the excellent unidirectional transport performance and antibacterial properties effectively prevents bacterial growth on cloth diapers.Additionally,the Janus fabrics exhibit excellent washability and biocompatibility,further enhancing their potential applications in reusable cloth diapers.
